13621381 has 2 divisors, whose sum is σ = 13621382. Its totient is φ = 13621380.

The previous prime is 13621373. The next prime is 13621409. The reversal of 13621381 is 18312631.

13621381 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8820900 + 4800481 = 2970^2 + 2191^2 .

It is an emirp because it is prime and its reverse (18312631) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 13621381 - 2³ = 13621373 is a prime.

It is a super-2 number, since 2×13621381² = 371084040694322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (13621331) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6810690 + 6810691.

It is an arithmetic number, because the mean of its divisors is an integer number (6810691).

Almost surely, 2^13621381 is an apocalyptic number.

It is an amenable number.

13621381 is a deficient number, since it is larger than the sum of its proper divisors (1).

13621381 is an equidigital number, since it uses as much as digits as its factorization.

13621381 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 864, while the sum is 25.

The square root of 13621381 is about 3690.7155132847. The cubic root of 13621381 is about 238.8216604605.

It can be divided in two parts, 136213 and 81, that multiplied together give a triangular number (11033253 = T₄₆₉₇).

The spelling of 13621381 in words is "thirteen million, six hundred twenty-one thousand, three hundred eighty-one".